Electric metallurgical furnace.



w. E. MUORE..

ELECTRIC METALLURGICAL FURNACE.

APPLICATION FILED JULY 30,1917.

1,293, 1 64. Patented Feb. 4, 1919.

UNITED sTATEs PATENT oEEIcE.

WILLIAM E. MOORE, 0F PITTSBUMH, PENNSYLVANIA.

ELECTRIC METALLU'BGICAL IUBN'ACE.

To al@ whom t may concern.'

Be it known that I, WILLIAM E. MOORE, a citizen of the United States, residing at Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented certain new and useful Improvements in Electric Metallurgical Furnaces, of which the following is a specification.

r.lhis invention relates to improvements in metallurgical furnaces, and one of its objects is to provide a furnace which shall combine advantageous features of both the induction type and the are type of electric furnace.

To start an induction' furnace, say of the kind employing a loop of metal which passes around the inductive element, it is necessary tol first ll the chamber of this loop with molten metal which, according to the present practice, is obtained from a fuel or other furnace. My invention overcomes the necessity for obtaining molten metal from some outside source such as referred to, by introducing into the metal chamber of the in-V duction furnace one or more electric arcs which may 'be used initially to melt a suicient amount of metal to fill the induction loop or loops, after which the arc may or may not be used.

On the other hand, in arc type melting furnaces, it is desirable to have a portion of the heat produced by one or more submerged inductive loops, which have the effeet of producing a vigorous circulation of 'the bath and effecting thereby an agitation especially desirable in the purification and manufacture of high grade and alloy steel in order to-dissolve the alloys.

The invention has for its further object the provision of an induction furnace wherein the pinch effect shall be reduced to a minimum.

lin order to more fully describe my invention, reference will be had to the accompanying drawings, wherein Figure 1 represents in vertical section av furnace embodying one specific form of my invention Fig. 2 is a section taken .on the line 2X'- x of Fig. 1; and

Fig. 3 is a detail fragmentary section of the modification of the inductive loop.

4 'The furnace here shown comprises, among other parts, a roof 1, side walls 2 and bottom 3, all of any suitable refractory mater1al. The bottom 3 has two extensions 4 and 5 Specication of Letters Patent.

Application :ned July 3o, m17. serial No. 183,567

vgular shape in cross section,

Patented Feb. 4, 1919.

which project downwardly from the bottom proper at an angle, as shown. These projections are pierced, respectively, by openings 6 and 7 causing the extensions to form two loops. In these loops are formed, respectively, channe1s8 and 9, each channel following the arc of a circle at the lower end of the loop, and gradually expanding or tapering upward where it merges into the chamber proper of the furnace. In cross section, these channels are oval-shaped, as shown in Fig. 2. They may, however, be of rectanas shown, for example, at 9 in Fig. 3.

The openings 6 and 7 receive coils 10 and 11 wound on cores 12 and 13 provided, respectively, with laminated yokes 14 and 15,

-the inner walls of the extensions 4 and 5 The heating coils 10 and 11 are excited from two separate transformers 20 and 21 on a two-phase circuit. If only a single heating coil is employed, a single-phase current would suffice. 1f three heating coils are employed, each would receive current from a. different leg of a three-phase circuit, and sc on.

With the construction shown, considerable hydrostatic pressure is maintained on the molten metal within the inductive loops. thereby greatly reducing theV action known as the pinch effect which tends to pinch of or rupture the stream of molten metal when forced to the high current densities A necessary for rapid heating. rlhe pinch effect is due to the constriction of the fluid stream by the magnetic forces circulating perpendicularly to the axis of current fiow,

is proportionate to the square of the cur-' rent, is resisted by hydrostatic pressure, and is reduced when the stream is of oval or elongated in section, due to the fact that the lines of force on opposite sides of the stream tend to neutralize each other by being brought closer together than would bek ther case were the-stream square or circular in cross section. My invention takes advantage of these ways of reducing the pinch effect.

Also due to the magnetic re ulsion radially from the inductive cores, t e outer layers'- of metal in the inductive loops tend to be forced upward and outward, and are replaced. by metal flowing down the inner sides of the loops. 4This causes a motive effect which results in rapid circulation'of the metal. For the purpose of facilitating this action, the loop channels 8 and 9 gradually expand as they extend upward into the main^chainber of the furnace.

The refractory material of the inductive.

loops is reinforced on the outside by a metalf `lic casing 22, cut or split, as at 23, to interrupt the electrical circuit formed byit.

While I have herein shown and described one specic embodiment of my said invention, vit will be understood that .the same may be modified in various ways without departing from the spirit thereof.

-Having thus described my invention, what l claim as new and desire to secure by Letters-Patent is l. An electric metallurgical furnace-comprising a chamber or crucible adapted to contain metal, means for heating the ymetal therein by an electric arc, an extension formed on the furnace bottom projectln downwardly therefrom to form a loopan having a loop channel therein communicat-v metal, means for heating the metal in said y chamber by an electric arc, an extension formed on the furnace bottom projecting downwardly therefromto form al'oop and having a loop channel communicating with the main chamber at the upper ends of the loop, and an electrical heating element in v inductive relation to the metal in said loop,

the upper ends of the loop gradually expanding upwardly from a point substan tially midway of the heating element to the point ofcommunication of the ends of the .loop with the main chamber.

3. An electrical metallurgical' furnace comprising a chamber adapted to containmetal, means for heating the metal in said chamber by an electric arc, an extension formed on the furnace bottom projecting downwardly therefrom to form a loop and having a loop channel communicating with v4the main chamber at the upper ends of the loop; and an electrical heating element in inductive relation to the metal in said loop,

the upper ends of the loop gradually expanding upwardly from a point substantiallyy midway of the heating element to the oint of communication of the ends of the oop with the main chamber, said channel being elongated in transverse section.

.4. An electrical metallurgical furnace comprising a chamber adapted to contain metal, means' for heating the metal in said chamber by an electricarc, an Aextension formed on the .furnace bottom projecting downwardly therefrom to form a loop and having a loopchannel communicating with the main chamber at the upper ends of the loop, and an electrical heating element in inductive relation to the metal in said loop, the upper ends of the loop gradually expanding upwardly from a point substantially midway of theheating element to the point of communication of the ends of the loop with the main chamber, said-channel being elongated in transverse section, and being substantially U-shaped in longitudinal section, the central axis of said U-shaped channel being inclined to the vertical.

5.v An electrical metallurgical furnace .comprising a chamber adapted to contain metal, an electric are disposed in the upper part of the chamber for heating the metal therein, a pair of extensions formed on the furnace bottom, said extensions bein angu- '95 larly disposed with respect to each ot er and to the central vertical axis of the fum'iace, each of said extensions having a channelin the form of a loop, said channels being of elongated transverse section and gradually expanding upwardly toward their upper ends and being in communication with said main chamber, and an electrical heating element around which each extension is looped.

6. An electric metallurgical furnace comprising a chamber or crucible adapted to contain metal, an extension formed on the furnace bot-tom projecting downwardly therefrom to form a loop and having a loop channel therein communicating with the main chamber, and an electrical heating element around which said extension is looped, said channel gradually vexpanding upward.

'f'. An electric metallurgical furnace comprising a chamber or crucible adapted to contain metal, an extension formed on the furnace bottom projecting downwardly ment around which said extension is looped,

said channel being substantially U-shaped in longitudinal section, elongated inA transverse cross section, and gradually expanding upward.

In testimony whereof I affix my signature.

WILLIAM E. MOORE. 

